# Relativity and charge

**URL:** <https://boards.straightdope.com/t/relativity-and-charge/338503>\
**Category:** Factual Questions\
**Created:** [January 5, 2006, 1:38am UTC](https://boards.straightdope.com/t/relativity-and-charge/338503 "2006-01-05T01:38:58Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\
**Post date:** [January 5, 2006, 1:38am UTC](https://boards.straightdope.com/t/relativity-and-charge/338503/1 "2006-01-05T01:38:58Z")

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I could’ve sworn I posted this back in the day, but since I cant find it, maybe I’ll just post again and get a new perspective…  
As you approach the speed of light, you encounter three relativistic distortions:

You flatten out in the direction of travel, your mass increases to infinity, and time slows to nothing.

What, if anything, happens to charge?

I mean, If you accelerate a single proton with a known quantity of charge (+1) up to close the speed of light, would the charge be seen to slightly increase, decrease, or not change at all?

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**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\
**Post date:** [January 5, 2006, 2:37am UTC](https://boards.straightdope.com/t/relativity-and-charge/338503/2 "2006-01-05T02:37:19Z")

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I thought I’d read that as you approach the speed of light the space-time shift (time looks more spacelike, space in the direction you’re moving looks more timelike) causes electric and magnetic fields to swap places, so a charged particle moving at near lightspeed looks like a monopole. But I could be totally wrong about this though.

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**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\
**Post date:** [January 5, 2006, 2:59am UTC](https://boards.straightdope.com/t/relativity-and-charge/338503/3 "2006-01-05T02:59:17Z")

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As I understand it, that’s exactly what magnetism is: changes in apparent electric charge due to relativity.

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**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\
**Post date:** [January 5, 2006, 5:35pm UTC](https://boards.straightdope.com/t/relativity-and-charge/338503/4 "2006-01-05T17:35:59Z")

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The charge is invariant. The electric field due to the charge is no longer spherically symmetric. It’s stronger in directions perpendicular to the charges motion, and smaller parallel to the direction of motion.